1. Field of the Invention
The present invention relates to a semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a semiconductor light emitting device that can realize superior light extraction efficiency by reducing the quantity of light traveling inside the device due to total internal reflection, and a method of manufacturing the same.
2. Description of the Related Art
Semiconductor light emitting diodes (LEDs), as one type of semiconductor device, generate light of various colors due to electron-hole recombination occurring at a p-n semiconductor junction when current is supplied. These semiconductor LEDs, greatly advantageous over filament-based light emitting devices, have a long useful life, low power use, superior initial driving characteristics, high vibration resistance and high tolerance to repetitive power connection/disconnection. This has continually boosted the demand for semiconductor LEDs. Notably, of late, a group III nitride semiconductor capable of emitting light at a short wavelength such as blue light has been highlighted.
However, semiconductor light emitting devices have limitations, one of which is low light emission efficiency. Light emission efficiency is determined depending on light generation efficiency and the efficiency of light emission to the outside of semiconductor light emitting devices. The internal quantum efficiency of semiconductor light emitting devices reaches approximately 100%, whereas the external quantum efficiency thereof is considerably low. This is because the total internal reflection of light generated inside the semiconductor light emitting devices is caused by different refractive indices of the devices and the air when the light strikes the boundaries of the devices. If light generated inside the devices strikes the boundary of the devices at an angle of incidence larger than the critical angle, the light is internally reflected without being extracted to the outside, significantly undermining the light extraction efficiency of the devices. Also, the light, which has failed to pass through the boundaries, travels inside the devices and converts into heat. This increases the amount of heat being generated by semiconductor light emitting devices, resulting in shorter useful life of the devices.
To solve this limitation, vertical type semiconductor light emitting devices or flip-chip semiconductor light emitting devices have been proposed by changing the locations of electrodes. However, the limitations concerning low light emission efficiency caused by total internal reflection still remain unsolved.